CI: Make caches last one week at most

.github/workflows/msys2-build.yml

@@ -51,7 +51,7 @@ jobs:
       id: xmake_cache
       with:
         path: ${{ github.workspace }}/xmake_git
-        key: MinGW-XMake-r2
+        key: MinGW-XMake-$(date +'%w')
 
     # Build xmake
     - name: Setup xmake
@@ -82,7 +82,7 @@ jobs:
       uses: actions/cache@v3
       with:
         path: ${{ env.XMAKE_GLOBALDIR }}/.xmake/packages
-        key: MinGW-${{ matrix.arch }}-${{ matrix.mode }}-${{ steps.dep_hash.outputs.hash }}-r4
+        key: MinGW-${{ matrix.arch }}-${{ matrix.mode }}-${{ steps.dep_hash.outputs.hash }}-$(date +'%w')
 
     # Setup compilation mode and install project dependencies
     - name: Configure xmake and install dependencies